I Just came across an Octave Box module and it is working.The only problem is that the knob has broken off, so the setting can not be changed.And there seems to be no way to re-attach the knob (I'm assuming a piece has broken off

I have some images of the offending parts but I do not know how to upload them.

A picture would help us with the visuals. I owned a octave box (gave it away at the last ElectraFest), and had it apart a few times. The adjustable knob on the case sits on top of a boxy blue micro potentiometer on the circuit board. The pot basically has a tiny metal slotted screw on top that the knob mates with. Worse case you should be able to slip a jewelers screwdriver in there to adjust it. Frankly, I did not notice a ton of difference with this adjustment... I assume it was for sensitivity, or something.

If you read that recently posted Leslie West interview, he even says in there a few times about the octave box that you can't play more than one note, and I think he tells the reporter to play staccato. I thought mine was defective, but after talking to others and reading up on them, I find that basically they were pretty primitive circuits. The fact that they work at all is impressive, but they are not up to todays expectations as far as performance. This was almost 40 years ago afterall. Best o luck, Mike.

If memory serves, that is supposed to adjust the decay time of the octave note. It says "sustain level" on the box.

Yes, the circuit is pretty crude. But the glitchy artifacts are one of the things that make it.... charming.

As Mike mentioned, if the knob is gone you can carefully use a small screwdriver to adjust the pot.

If the plastic shaft is broken, you may be able to find a replacement potentiometer. It would require taking the box apart, unsoldering the broken one, and installing a new one in it's place. Value, taper, physical size and lead configuration would have be considered carefully when choosing a replacement part. But I'm sure there is something available that would work.